In the surface mining etc., there is known an autonomous travel system in which dump trucks (hereinafter referred to “unmanned dump trucks”) that perform the autonomous traveling without driving by an operator are communication-connected to a management control device via a wireless communication channel and each of the unmanned dump trucks is managed and controlled.
Regarding the management control method, there are known a method whereby a spatial relationship between vehicles is grasped by performing communication with all vehicles frequently and instructions of deceleration, stop, etc. are transmitted, and a so-called block control method of preventing vehicles from collision by giving a travel permission section exclusively to each vehicle and controlling or managing the each vehicle to travel only in a section given to the each vehicle. Although with the former method, it is easy to perform more flexible control between the vehicles, it is necessary to communicate with all the vehicles with high frequency, and there is a demerit that a load on wireless communication is large. In contrast to this, although the latter block control method requires adjusting a spatial relationship between vehicles, a vehicle distance, etc. depending on how to give the travel permission section, since frequency of communication just requires existence of timing of updating the travel permission section, it has a merit that a load on the wireless communication is low.
Generally, a wireless communication system used in a mine has a feature that an allowed communication capacity is small in order to design it with enhanced reliability. Moreover, in the mine, complicated geographical features have influences, and communication disruption also occurs frequently. Therefore, it is desirable that communication frequency be as few as possible. Therefore, it is desirable to use the block control method for management control of the autonomous travel system in the mine.
Incidentally, in the surface mining, when multiple unmanned dump trucks are traveling, there may occur a situation where the unmanned dump truck traveling ahead of a subject vehicle stops due to a sudden failure and a necessity for the subject vehicle to overtake the forward stopped vehicle arises. As one example of this overtaking technology, Patent Document 1 discloses a configuration that specifies as follows: “Based on a monitoring result of a travel state of the travel path, an entry prohibition area is set ahead of one vehicle that travels one lane among two lanes for both directions, and a travel command that makes the vehicle travel in a part of a section of the opposite lane that opposes one lane while avoiding the entry prohibition area is given. To an oncoming vehicle traveling in the opposite lane, a travel command that prohibits entry into some sections is given. Moreover, an upper speed limit in a condition setting section of the travel path is set, and travel conditions including the upper speed limit that was set in association with the condition setting section are given to the vehicle as a travel command. When the travel command is given, the vehicle travels the travel path at a speed that does not exceed the upper speed limit.”